The use of a nerve stimulator in difficult carotid surgery

Abstract

Cranial nerve injury after carotid endarterectomy is a well-recognized complication. The published incidence of this complication ranges from 11% to 14%.1Forssell C Kitzing P Bergqvist D Cranial nerve injuries after carotid artery surgery. A prospective study of 663 operations.Eur J Vasc Endovasc Surg. 1995; 10: 445-449Abstract Full Text PDF PubMed Scopus (62) Google Scholar, 2Schauber MD Fontenelle LJ Solomon JW Hanson TL Cranial/cervical nerve dysfunction after carotid endarterectomy.J Vasc Surg. 1997; 25: 481-487Abstract Full Text Full Text PDF PubMed Scopus (82) Google Scholar The vast majority of these are traumatic neuropraxias that resolve completely. The cranial nerves most commonly affected are the hypoglossal (7.5%), vagus (4%), facial (2.5%), and glossopharyngeal (0.3%).1Forssell C Kitzing P Bergqvist D Cranial nerve injuries after carotid artery surgery. A prospective study of 663 operations.Eur J Vasc Endovasc Surg. 1995; 10: 445-449Abstract Full Text PDF PubMed Scopus (62) Google Scholar, 2Schauber MD Fontenelle LJ Solomon JW Hanson TL Cranial/cervical nerve dysfunction after carotid endarterectomy.J Vasc Surg. 1997; 25: 481-487Abstract Full Text Full Text PDF PubMed Scopus (82) Google Scholar, 3Ballotta E Da Giau G Renon L Name S Saladini M Abbruzzese E et al.Cranial and cervical nerve injuries after carotid endarterectomy: a prospective study.Surgery. 1999; 125: 85-91Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar, 4Maniglia AJ Han DP Cranial nerve injuries following carotid endarterectomy: an analysis of 336 procedures.Head Neck. 1991; 13: 121-124Crossref PubMed Scopus (54) Google Scholar, 5Vasquez G Mascoli F Buccoliero F Occhionorelli S Santini M Iatrogenic lesions of cranial nerves during endarterectomy of the carotid artery [Italian].Minerva Chirurgica. 1994; 49: 813-817PubMed Google Scholar In the setting of redo carotid endarterectomy or endarterectomy on a previously irradiated or scarred neck, there is a higher risk of inadvertent nerve injury (19%).6O'Donnell TF Rodriguez AA Fortunato JE Welch HJ Mackey WC Management of recurrent carotid stenosis: should asymptomatic lesions be treated surgically?.J Vasc Surg. 1996; 24: 207-212Abstract Full Text Full Text PDF PubMed Google Scholar We recently performed a right-side carotid endarterectomy for a symptomatic 90% internal carotid artery stenosis not thought to be anatomically suited to transluminal angioplasty. The patient, a 74–year-old man, had undergone right hemiglossectomy and functional neck dissection for squamous cell carcinoma of the tongue 4 months previously. Postoperative bleeding at that time had required further neck exploration and ligation of the right internal jugular vein. The patient suffered a right frontoparietal cerebral infarct during or just after this second procedure, which was subsequently found to be the result of a high-grade carotid artery stenosis. After a 6-week recovery period, he was referred to our service and scheduled for right carotid endarterectomy, which was performed under regional anesthesia. The previous surgery was found to have resulted in significant scar tissue, making it impossible to visualize the hypoglossal nerve. Therefore, we decided to use a peripheral nerve stimulator (750 Digital, Bard Biomedical, Mass) to facilitate the localization of the nerve. The patient was asked to stick out his tongue and, with the stimulator earthed to the patient's forehead, a sterile hypodermic needle connected to the live terminal was moved systematically over the area until an ipsilateral twitch was observed in the patient's tongue. The current was then reduced to allow maximal accuracy of localization, and dissection proceeded on the basis of this. The hypoglossal nerve was identified and protected during full mobilization for what was found to be a very high lesion. The carotid endarterectomy proceeded without event, and no postoperative hypoglossal nerve palsy resulted. Although we would certainly not advocate this technique as a replacement for anatomical knowledge and careful dissection, we would suggest that it is useful when difficulty in localizing the hypoglossal nerve is encountered in a hostile surgical field. This technique is well recognized in parotid and thyroid surgery, but, to our knowledge, has not been described in the context of carotid endarterectomy. Clearly, the use of this adjunctive technique is only possible when carotid surgery is performed under regional anesthetic in the awake patient.